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Old 01-16-2013, 01:31 AM   #1 (permalink)
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Trailer Canopy Evaluation

I picked up a used Ute (Pickup) canopy the other day, not bad condition for a freebie, I want to look at the feasability of using it as a trailer cap, just mounted on an angle so it simulates the template profile.
I've just blocked it up temporarily to take a couple of pic's below:





The trailer is basically a 6'x4' with a short drawbar so it is only 9' from tip to tail and hides completely behind vehicle when towing.
The Canopy is just over 7' long and 5' wide at base (4' across top), the profile matches vehicle well, vehicle is about 3" wider on each side on the upper body and about 6" wider each side at mid to lower body so it will easily hide in the wake. At a rough guess the rear area of trailer is about 50% that of vehicle, so I am hoping this will show up in FE.

If mounted it will overhang about 16" at front of load area and about 3" either side, with about 4" of the wheel guards still protruding either side.
The front of canopy will be just over 2' from car body, this should be enough for normal driving and manouvering, but I will need to make up a hitch extension for tight spots, not to be used for towing though. There is also the possibility of lowering rear of canopy about 2" more and possibly pull the base in about 2" either side, still need to work out complications of mounting issues with that distortion and that would entail also replacing rear glass door, so may not be worth the effort.

I considered mounting it backwards, but there were too many issues so if I go ahead it will be mounted in this format, it will be a hinged at front and the rear will be raised with gas struts to just above level for access, I need to build angled sides and a toolbox/storage in the front under canopy, will probably remove and seal up front window, side windows and roof racks.

The way it is propped it is sitting at around 10* (by protracter & calculation) and the roof of vehicle is in line with top of front roof rail, so the 10* line crosses the vehicle roof about 6" above so this should allow a more gentle transition and the canopy should fill wake area well.

The roof of canopy is recessed about 2 1/2" and has 4 or 5 channels moulded in length to give strength, if I go ahead this can be foamed & glassed over to give a smooth surface. Hitched on flat road the trailer is slightly nose down maybe 2" higher than underside of vehicle overall so if the underside air is contained it should act like a long diffuser.

If it happens all the usual add on's around trailer wheels, skirts, fairing etc. small Kamm on canopy rear, cushioned rounded front on canopy and as much gap sealing as possible will happen over time.

At this point my main issue is to answer the fundamentals:
1 / Are the angles ok? it is 10* on canopy roof and about 7.5* from vehicle roof to canopy roof (front lip), I could build up this area say 1-2" to get down to around 5*, with a bit of rounding it could make a nice transition. I am also planning a small Kamm on back of vehicle to minimise gap area.

2 / Should I be concerned about any lift issues, weight is not a problem the canopy should come down to 100lb alone and if I am careful other add on's will come to less than that, so carrying capacity should still be good.

3 / Would my time be better spent starting building a custom design for that vehicle trailer combo? Just thinking about Aeroheads trailer a hell of a lot of work trying to make a not so perfect free boat hull fit a perfect template, good results, but it may have been easier to do a ground up design.

4 / Are there any other "show stoppers" and pitfalls I should be aware of?


Last edited by Tesla; 01-16-2013 at 02:13 AM..
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Old 01-16-2013, 10:10 AM   #2 (permalink)
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I think this is a great project. I will be watching with interest. As far as construction goes I would continue with your mockup with the idea of possibly building a fiberglass/foam version to mount to your trailer once everything is sorted out. Just my opinion.
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Old 01-17-2013, 07:58 PM   #3 (permalink)
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canopy

I would recommend a custom build if you want to eek out all the mpg that you can.
I don't regret my Viking project,but wouldn't go down that road again.
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Old 01-18-2013, 03:26 AM   #4 (permalink)
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I think the biggest problem the part you have has is that it doesn't taper to the rear. I wouldn't bother smoothing the corrugations on the top.


Here is the part I have to work with. It does have a big end and a little end (shown backwards), but even with that I calculate I would need to pie cut it and narrow the back another 6-8". So far I choose not to.
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Old 01-19-2013, 08:46 AM   #5 (permalink)
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Quote:
Originally Posted by turbothrush View Post
I think this is a great project. I will be watching with interest. As far as construction goes I would continue with your mockup with the idea of possibly building a fiberglass/foam version to mount to your trailer once everything is sorted out. Just my opinion.
Thanks for posting
Looking like there is a good chance it will stay just as a prop and have to wait for the custom build, may just mount it flat in the interim period for utility purposes.

Quote:
Originally Posted by freebeard View Post
I think the biggest problem the part you have has is that it doesn't taper to the rear. I wouldn't bother smoothing the corrugations on the top.

Here is the part I have to work with. It does have a big end and a little end (shown backwards), but even with that I calculate I would need to pie cut it and narrow the back another 6-8". So far I choose not to.
That's kind of where I am, trying to determine how much work is required and when it will hit the point of diminishing returns. There is a slight sideways taper created by angling up, but the base is a bit wider than the concept in my head anyway.
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Old 01-19-2013, 08:52 AM   #6 (permalink)
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Quote:
Originally Posted by aerohead View Post
I would recommend a custom build if you want to eek out all the mpg that you can.
I don't regret my Viking project,but wouldn't go down that road again.
Thought you might say that, I am still evaluating it,
If I can keep it simple & cheap it may have some aero benefit along with the utility aspect.
But the main problem I see, outside of imperfect aero is by angling up it already draws attention and if it looks NQR then it will be a red flag for the boys in blue.
A custom built unit, done well, will just look like a cute teardrop camper at first glance, so may need to think about planning in some flush mount windows/access hatches to complete the image.
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Old 01-19-2013, 04:47 PM   #7 (permalink)
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Old 01-19-2013, 05:18 PM   #8 (permalink)
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simple

Quote:
Originally Posted by Tesla View Post
Thought you might say that, I am still evaluating it,
If I can keep it simple & cheap it may have some aero benefit along with the utility aspect.
But the main problem I see, outside of imperfect aero is by angling up it already draws attention and if it looks NQR then it will be a red flag for the boys in blue.
A custom built unit, done well, will just look like a cute teardrop camper at first glance, so may need to think about planning in some flush mount windows/access hatches to complete the image.
I you can keep it in the wake,and it doesn't protrude out into the unmolested flow,it will probably be a wash.
Any kind of body structure will keep the elements and eyeballs off your belongings.And if the constabulary takes a dim view of 'Eigenbau' road gear,maybe its best to grab whatever 'production' pieces you can find for the build.
PS If curious about performance,a flat-black construction,with proper lighting,and tested only after dark,can yield some useful mpg numbers.
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Old 01-19-2013, 07:15 PM   #9 (permalink)
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Quote:
Originally Posted by aerohead View Post
If curious about performance,a flat-black construction,with proper lighting,and tested only after dark,can yield some useful mpg numbers.
Aero Stealth, I like that not seen or heard.
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Old 01-20-2013, 04:02 PM   #10 (permalink)
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Is the angle of the canopy roof sloping down at about 10 , or are you trying to match the template 22 ?
Would you need to add a spoiler to the aft end of the canopy?
just my 2,
kenny

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